Method of utilizing steel-scrap



Patented Apr. 6, 1929.

600 26's Stem@ 50u10 6. s 663 Cdkg APPLIS-ATWT( FILED JUNE, 1912A G. M. MUNTZ AND ff. Pv?. RUBIEU. METHOD of umzzma STEEL SCRAPl UNITED STATES PATENT OFFICE.

GEORGE M. MUNTZ AND ETIENNE M. ROUBIEU, 0F BROOKLYN, NEW YORK, ASSIGNORS T0 TROPENAS COMPANY, 0F

BROOKLYN. NEW YORK, A CORPORATION OF NEW YORK.

METHOD OF UTILIZING STEEL-SCRAP,

Specification of Letters Patent.

Patented Apr. (i, 1920.

application filed June 25. 1917. Serial No. 176,849.

To o!! 1li/oni 'it may concern lle it known that we, (nonci: .\l. illrn'rz and ETIENNE M. Romano, citizens of the United States of America, and residingat Brooklyn, New York, and havingDr a post office address at 2243 Nostrand avenue, Brooklyn, New York, have invented a certain new and useful Method of Utilizingv Steellcrap, of which the follruvingA is a specification.

Our invention relates to a method of utilizing; steel scrap and our ohjeet is to provide an iniproved cupola practiee by which a larger pereeutage of steel scrap may he utilized than has hitherto heen possible when `tl|e rupola is operated in accordance with established practice.

lt is of course common prat-tice to melt in the cupola a mixture of pig iron and steel scrap; but hitherto the proportion of steel scrap has rarely exceeded 40 per cent. ot the .metallic charge and frequently has not reached as high a proportion as this. This low proportion of steel scrap in the complete charge has been a neressary incident to the defective. method commonly einployed in operating the Cupola. ln rernedying this. We have found, for instance. that for a converter operation or blow, when the cupola is supplying molten charges for a converter. we can successfully haelt as high as 90 por cent. of scrap to l() per cent` of piga ligure liever heretofore, approaehed so far 'as we are aware, While in running,r the cupola continuously, as for gray Airrn or malleable iron Y proportion of pig' iron usedis negligible. Inasrnuoh as steel sera p is far cheaper than pip.r iron the saving incident to the use of lour improved method is readily appreciated.

Meltingr in a cupola is usually accomplished hy su perposing alternate amounts of metal and fuel on a previously ignited hed of fue] and enhancing oon'dmstion ofthe fuel hy-the application of a blast of air through suitable twyers. The various amounts of metal and fuel entering the cupola alternately are usually called metal oh'aiges and fuel charges, respectively. In

foundry pmctiee` the melting'steel scrapr not only is a higherA temperature necessary than for melting pig iron, but also a greater quantity of fuel than is necessary to produee that higher teur peinture. since the steel absorbs from the fuel a' contain amount of carbon, which otherwise would contributo to increase temperature. ln other words, fuel inust be supplied in suflicient quantity not only to allow the incvitahle reearhurization of the steel, hut also to fuse the metal at a temperature sullieiently high to maintain it iuniolteu vondition ou the hearth of the cupola and prevent it from solidifyinn there. This trouble has been understood and it has been atti-nlptcd to moet the situation hy increasin; the amount of fuel which is usually in sei-ted between alternate charges of metal. For the reason hereafter explained. this has failed to accomplish the desired result, und it has heroine general prat-tice to use only a slightly inereased amount of fuel and to linut the proi'iortion of scrap to pig iron to l'roin 250% to 40p; of scrap to 70?? to 60% of pigr and even a lower proportion of Scrap in order to keep thel molten product from solidifying on the hearth. Furthermore, the practife heretofore followed has heen to charge the scrap directly upon the fuel and the pig above the scrap. with the thought that the pig would melt first and run down through the strap and thus aid in the fusion thereof.

Uur investigations ha ve disclosed that the prartire heretofore followed has been defective in several respects: first of all by reason of failure to heat properly the hearth of the furnace before actual melting is hegun, and second infailin'g' to sulrdivide the alternate charges of nieta'l and fuel to a suffir-ient extent to obtain the desired result, and third in failure properly to charge the metal upon the fuel bed or fuel charges.

Willen the usual full sized charge of metal is fed to the cupola and contains a large proportion of steel` sera p, the increase/d amount of fuel required to melt and reear hurize the steel scrap is too deep to be completeljy ignited sin'iultaneously throughout its depth. with the result that the lower portion of the fuel is reduced to ash before the upper portion is fully red and the portion the hearth. Ve have found that this dill'iculty is completely eliminated by subdividiug the charges. If, for instance, the nor mal charge is 1200 pounds of metal, we divide this in half and make our charges G00 pounds of metal and in like manner halve the fuel charge, so that if the latter com prises normally 12() pounds of coke, we use foi-'our sub-divided charge, say UU or (35 pounds of coke. Moreover, we have discovered that the assumption that the pig will melt first when charged above the scrap, is erroneous and that as a matter of fart the scrap melts first and the pigz,r afterward so that no advantage is obtained by charging in the customary manner, but on the other hand an advantage is lost since if pig is charged directly on the fuel, its fusion ro luces a bath of metal on the hearth w iieh owing to its very high temperature and its lower solidifying' point will aid in inaintainiupr the subsequently melted and recarbu rized steel scrap on the hearth in propel' fused condition.

Moreover, b v charging the pig first it is assured that the molten product on tlnl hearth and at the tap hole. is of such char arter that it remains in fused condition at a lower temperature than the molten scrap and 'o prevents the formation of a solid or semi-,vlastio plug at the tap hole thus affording easy tapping-a most important consideration. lf the metal falling first on the hearth is the fused scrap, which re- (uires a high temperature to maintain its fused condition. it is extremely likely that a plug of solidified metal will form at'the tap hole which cannot be punctured by the tappin; r bar. with the result that the entire molten mass solidifies on the hearth of the cupola before it. rauhe withdrawn.

Other variations from established prac tice will be observed from the following` ex ample of the manner in which meltimgr is accomplished in accordance with our process.y Assuming the cupola to he. empty and the lighting and the tap holes at the4 hearth level are open. a fire is huilt upon the hearth and a suitable fuel hed extending from 12 to Ht inches above the top twyers laid thereon.- 'lhis is ignited and after it is well fired,

a 2l' to El footl layer of fuel is charged thereon and the blast applied. The fresh fuel forms a cork or plug which forces the heat flown upon the hearth. the lighting and tap holes being still maintained open to permit the escape of the. products of combustion. This preliminary heating of the hearth. which is continued for 15 to 25 minutes, brings' the hearth into velv hot condition. which is desired for the reception -of the molten metal. A further supply of fuel is then charged upon the tire bed.if necessary, to bring the ripper level of the fuel to the melting zone, that is to say, ll or 15 inches above the twyers and the li hting door and the tap hole are closed so t at the products of combustion will pass normally upward to the stack. Upon this fuel we charge a small quantity of pig iron which we call the priming' pig;r iron, and above the pig,r iron a quantity of steel scrap. Assuming the cipola to e 36 inches in diameter inside t ie lining, of a capacity of about 5 tons perliour, the first metal charge would be say 200 pounds of pig' iron followed by 40() pounds of steel scra i, instead of the usual charge of 1200 poum s of metal. Upon this weadd a layer of fuel, say 65 pounds of coke, then a layer, say of (50() pounds, of scrap, and so on. As the charges move downward through the melting zone above the twyers the relatively thin fuel beds are quickly and completely ignited throughout their depth and gire their entire heat to the superposed charge of metal which rapidly fuses so there is practically no interruption of the rain of molten metal to the hearth. Owing to the high teni erature of the fused scrap and the relative y low melting point of the primer of pig iron, the resulting molten product has no tendency to solidify or the tap hole to become choked. The charges of .scrap may succeed each other continuously without interruption as longr as the operation of the. cupola is continued and in this rase the proportion of the original quantity of priming pig to scrap is negligible. lf, however, the operation is interrupted,` a primipg charge of pig iron is introduced at such a. time that its subincent fuel bed reaches the melting zone substantially simultaneously with the cutting ofl' of the blast` so that it is in position to form a primer when the operation of the cupola is resumed. lVhen the cupola is associated with a converter, the successive charges are so calculated that upon the halt of the op-k eration of the cupola a priming charge of pigrr iron will be inl a position to enter the melting' zone when the blast is again starte. ed. Preferably each charge will comprise a small proportion of pig;r iron to steel scrap so that the blast may be cut ofil at any time and the. presence of A,priming pig assured when the blast .is started agai ln the accompanying drawing we have shown a cupola in `vertical section to illustrate the operation of the present method. The cupola 1() is shown in condition for the beginning.. of the meltafter the preliminary heating of the hearth is completed and the lighting` and tapping holes 1.1 and -12 are closed. The fuel bed 13 extends from the 'sand bedv 1l toa point above the twi/ers 15,

while the primer 16 of easilyfused material enters the fuel bed 13. The primer is here shown as eoioprisin' say 200 lbs. pig iron next tothe fuel bed, and 3l-00 lbs. of. steel scrap saperposed thereon. Successive relatively light, layers oil fuel 1T anu steel srrap IH are dumped into the Cupola through the rharging door lll.y and the eventual melt drawn ol'l through the lower tapping hole 12A Obviously the pig r primer is lirst melted and maintains its position at the hottoln of the melt on the sand hed lfi` and particularly at the tapping hole l2, toward which the sand hed slopes.

lVhile an)Y suitahle metal for the primer may he elnploymil, it is an added eeonourr to use a portion of one olt the melts oi' the preceding' (lay: thus a lieu' spel-iai charges' may he melted at the und ol vri-ry day7 and divided into small portions and these poi'- tions' used to l'orlu the primers for theoperM ations of the next day. This is merely a nlatter of added eronozn)v sinre the cupola product is less expensive than pig iron. Ferrosiliron is pl'et'eral'lly used as a primer where the cupola is asrlouial'ed with a ron4 verter for the produifiion ol' steeh ns this special pig' iron silipplies' the neeeesnrr amount oi sliron in the molten produet to insure satisfactory relining' in the convertir. To also prefer to use steel sei-np lou' in phosphorus and sulfur inusrnnrh as no refining' for these elenu-nts is eontemphited in the Cupola. that ingredients may he added as necessary to vary the product as' ma;v he desired for ditlerent types of iron o1' steel.

As an example ol suitable charges l'or a, 3G inch Cupola assoiiated with n rouvl'rtler for the produetion ot' ei'eeh the following' ma)y he given, using' standard 9H terri siliton:

8% 3U pounds priming pir, al i .Y 19% H5 pounds ferro iieun nt, Y #555 pounds steel Semp at (uhu pounds converter charm :it fallout ik l A A .UW, l lining 12?? standard terrosilieon tlnl tot lowing' proportions Vwould he utilized :V

' Silikon,

87 pounds turrrisilieon a! e Y. 4&3 pounds steel scrap at about. v. Y i l Y 100, 0% LiLIU pounds converter charge :n nhulu i ense to use a high percentage ot pin' iron in the untlal one or lu'o rharges aud a higher proportion srlnp in the later rlinr'gges.l Euit thisI i;-' not sfzl'e when the rupola is. :issorialed ith :i fonwrter unless' tlu` unna-- bei' of rharges for a lilou' nl' the converter lt is of course understood' 'elauu as our invention and we (lo not lixnil ourselves to the use 0f the proportions ineniioned or to the detalls of operation sperlulieti.

Vile claim:

l. The method. of melting: steel a rupola, which consists in Y ignited hed of fuel upon the hearth ol' the cupola, charging a plug of fuel upon the ignited hed, highly heating the hearth hy down blast of the tire thereon, closing the bottom openings of the hearthl` charging Hufiieient fuel on the tiri o bring.r the fuel. heil to the level oi the melting' zo'ieialiove the twyers, charging' thereon a quantity of metal ol lower fusing point than steel scrap to form a fused primer on the hearth, and thereafter adding successive, relatively small rhairges oi fuel and o1 metal alternately, the metal comprising steel scrap in a quantity largely in excess of metal of lower fusing point.

L. The method ot' melting steel scrap in a cupola, which comprises the steps of highly preheating the hearthj ther lzetter initiating the melt with metal of lower fusing point than steel scrap, and thereafter meltingr relatively small f'harges ot' metal comprising steel scrap in a quantity largely in excess of metal of low melting' point employed in t'he operation ol the rupola.

SES. The method of melting steel sernp in a cupola which comprises initiating' the melt with metal of lowerfusing point than steel scrap, and thereafter melting successive metal charges eon'iprising steel Scrap largely inexevsa otlnivtal of low melting point, the size-r; o' the ehflrpgrs being surh as to insure a Substan i: lijf eo'x'itinnous rain of molten mettiti at n high temperature to the hearth of the cupola.

l. The metliofl nt melting' steel scrap in a r'upola which rnnsifsrs in first meltingif :1, quantity ot" metal of louv 'fusing point Lo cover the tapfhole at the hearth ot the rupola and therentter melting' steel Se'ap largely in excess thereof.

ln rupola praetiee, the step of preheating the hearth hy down dra ft of a` lire there` on, stopping theidown draft und thereafter melting metal ahoi'e the i'uel hed.

(S. The method olI melting' steel scrap in a rnj'iola which mnsis'ls' in initiating' the melt n'ih nieta! ol' lower fusing` point than steel wrap :xui introducing' into the cupola during' itsl operiinn sur'sfessiw ohurg'es ol' l'ueh steel scrap: nid instel nl' lower melting' poinL srrap in providing an l. Ll l) the metal of lower melting: point beingr superposed on the fuel und the steel scr-rip tliereabove.

T. In the melting of steel scrap in :i cupola, the stepsV of introducing! into the cupola during its` operation u charge of fuel` steel scrap, and metal of lower melting' point, the metal of lower melting point lleingr superposed ou the fuel und the steel scrap thereebove, and halting the blast as the charge reaches the zone ol fusion u hereby n primer of metal of lower fusing point thun Steel scrap is provided on the resump tion of the operation of the cupola.

8. The method of meltinff steel scrap in n,

eupolu which Consists in introducing during the operation of the cupola successive elim-ges of fuel und metal, the metal comprisinglr steel wrap in excess of metal of lower vfusing point.Y in the proportionof, for a thirty-six inch cupola, about sixty pounds of jtiuel und about six hundred pounds of metal in order to insure u substantidll)v vontimious rain of molten metal et a high temperature to the hearth of the cupola.

In testimony whereof we luwe signed our naines to this Specification.

(HQORGE M. MUNTZ.

E'lIENNE M. ROUBIEU. 

